In the trucking industry it is found that the operation of transport trucks under normal road speeds induces a significant zone of reduced pressure at the rear of the vehicle, which in turn tends to create low pressure conditions within the vehicle. Under wet conditions--including especially rain, snow and slush--this leads to the ingress of undesired quantities of moisture that can lead to marked deterioration in the cargo being shipped. The damage occurs by ingress of the water, and its impingement on the cargo--which is usually crated and/or contained in cardboard boxes. Of course, once wetted, the cargo may no longer be of value; or at least it may be in an unacceptable condition to the consignee.
One partial solution to this problem has been the provision of a temporary protective sheath stapled to the walls of the vehicles. This however requires to be penetrated each time that the load is accessed, and is expensive, time consuming, and difficult to maintain between partial unloadings.
One form of truck rear enclosure comprises a roll-up door, having a plurality of transverse steel slats carried in channels, for sliding displacement from a horizontal stowed location above the door, to a deployed condition, sealing the doorway as a transversely slatted rigid closure. This arrangement is extremely heavy, difficult to deploy, and subject to severe jamming if damaged in the normal wear and tear of the trucking industry. Consequently it is seen only in specialty vehicles.
It has been found that the provision of a non-sealing impermeable curtain is surprisingly effective in limiting moisture penetration to the cargo space, while the location of the curtain roller adjacent the top of the door aperture provides substantially unimpeded access to the vehicle interior,when the curtain is retracted onto its roller.
It will be understood, in accordance with road safety and vehicle safety regulations that exterior doors are generally employed in combination with the subject curtain. However, the necessity of achieving a tight seal by such doors is now deemphasized in light of the present invention.
The present invention provides, in combination, a truck having an enclosed body, a large rear aperture comprising substantially the full cross section of the enclosed body, at least one door for substantially blocking the rear aperture when in a closed condition, and a roll-up curtain positioned within the truck body adjacent the rear aperture. The curtain structure has a roller rotatably mounted adjacent the top of the body and extending transversely thereacross in substantially parallel relation with the door when the door is in a closed condition, and a flexible curtain mounted on the roll for downward unrolling displacement therefrom. The flexible curtain has a tongue portion to overlie a portion of the floor of the truck body located inwardly of the aperture, and the flexible curtain means fills substantially all the aperture when in an extended position so as to limit the ingress of moisture therepast. The flexible curtain is withdrawable upwardly in wrapping relation with the roller, and in substantially non-blocking relation with the aperture.
While optimum results appear to accrue from the use of impermeable, high quality polyester or other plastic materials in the curtain construction, the use of more permeable, lower cost material may achieve sufficiently effective moisture control to warrant the adoption thereof.